Russia completed on Friday (12 August) the multi-billion-dollar construction of an abandoned Soviet-era dam complex in St Petersburg to protect its former imperial capital from potentially devastating floods.The project was launched in 1979 but was abandoned and left to ruin after it proved too costly following the 1991 Communist collapse.Prime Minister Vladimir Putin, who has strong ties to his hometown and personally ordered the revival of works in 2005, hailed its opening a "historic event"."I remember well how I first came here in 2005 to look at it. It was simply a dump of concrete and metal scrap," he said."I had a feeling it would be impossible to restore."The completion of the dam ahead of parliamentary elections later this year is a showcase achievement for Putin at a time when leaders have faced criticism over deadly disasters blamed on lax safety and chronic corner cutting on Russia's Soviet-era infrastructure."Because of the completion, the city will not only obtain a system of protection from its age-old ills, from floods... This is an important event for all our citizens who enjoy the Northern capital," Putin said.Scientists say water levels are rising and flooding in the city of five million people, seen by many Russian's as the country's cultural heart, has been more frequent and costly in recent years.A 4-meter rise in water levels would cost an average of 150 billion roubles ($5.29 billion) in damage, according to government statistics, and threatens the city's historic centre, a UNESCO-listed World Heritage site and home to the 18th-century Hermitage and Winter Palace.The 109-billion-roubles ($3.85-billion) steel and concrete structure, stretching 25 kilometres (15.5 miles) across the Gulf of Finland, was designed to hold at bay water levels rising up to 5 metres.Putin, who started his political career in the St Petersburg mayor's office, assigned the completion of the project to business tycoon Vladimir Kogan, a close ally.Kogan said he would now step down as director of the flood barrier. "I was assigned to finish the construction... My mission is complete," he told reporters.